Impulse sender for use in telephone or like systems



y 4 c. c. PUCKETTE 2,281,994

IMPULSE SENDER FOR USE IN TELEPHONE OR LIKE SYSTEMS Filed Dec. 2, 1939 INVENTOR CHARLES CLARKE PUCKETTE B u :zfiXX ATTORNEY Patented May 5, 1942 IMPULSE SENDER FOR USE IN TELEPHONE R LIKE SYSTEMS Charles ClarkePuckette, Coventry, England, assignor to The General Electric Company Limited, London, England, a British company Application December 2, 1939, Serial No. 307,302

- In Great Britain December 17, 1938 3 Claims.

The present invention relates to impulse senders of the type provided on telephone subscribers instruments and operated by rotating a disc by a finger or the like, and has for its object the provision of improvements regarding the means for returning the finger plate to a normal position.

This finger plate, when in use, is wound against the pressure of a coil spring, the movement of the plate being restricted in one known form,

by the engagement of a moving stop with a fixed stop, the latter being fastened to the base of the impulse sender. In order to allow the spring to be wound or unwound, the moving stop is retracted by means of a screwdriver from the front of the impulse sender. This is objectionable in that a hole must be left in the front for the screwdriver access, this allowing dust and foreign bodies to penetrate inside the impulse sender.

According to the invention, in an impulse sender of the type hereinbefore mentioned, a central shaft which is rotated by the finger plate carries a pin which engages with a projection on a fiat stop-member which is fixed at one end and tensioned to rest against a screw at the other, the said screw projecting from the rear of the impulse sender in such a manner that the stop member can be moved into and out of the path of the said pin by suitable manipulation of the screw.

In one embodiment of the invention, the main shaft of an impulse sender carries a toothed wheel, the said wheel bearing a pin which engages with a projection on a flat stop member which is bent at one end through an angle of 180, and fixed at its lower end by two screws to the base of the impulse sender. The heads of the screws project through the flat upper portion of the stop member and act as locating devices.

The other end of the stop member is tensioned so as to rest against a screw the head of which is outside the base of the impulse sender. Rotation of the screw removes the projection of the stop member from the top of the pin and enables the spring attached to the central shaft to be wound or unwound as required.

Reference should now be made to the accompanying drawing, Figure l of which shows a front view of a portion of an impulse sender mechanism incorporating a stop according to the invention, while Figure 2 is a sectional view of the same mechanism.

From the drawing it will be seen that the sender comprises a base plate I in which is mounted a bush 2 carrying a central shaft 4. This shaft is rotated by a finger plate (not shown) which is fixed to the top portion 6 of the shaft, and is located relatively thereto by means of the pin 5. This finger plate is of known type and cooperates with a finger stop (not shown) in order to obtain impulses of the required number in any particular impulse train.

In order to limit the extent of rotation of the shaft a further pin 1 is provided, this pin projecting from the underside of a gear wheel 9 which can either be mounted on or formed integrally with the central shaft. This pin engages with a projection 8 on a fiat stop member I 0, which is fixed by screws II at one end to the base plate and tensioned so that its free end l2 rests against the head of a screw 14. The head of this screw is outside the base plate of the impulse sender, and reverse rotation of the screw, which can be effected without opening up the impulse sender, allows the stop member 8 to be retracted out of the path of the pin 1.

The shaft 4 is normally held in the position shown, i. e. with the pin 1 against the projection 8, by means of a coil spring mounted on the lower end of the shaft and omitted from the drawing for the sake of clarity. Thus removal of the stop from the path of the pin enables this spring to be wound or unwound, affording adjustment of the tension available in the spring for returning the finger plate and shaft to a normal position when wound up by the finger and let go. The stop 8 not only prevents the spring from unduly unwinding and so rotating the finger plate beyond its normal position, but it also prevents overwinding of the spring since the pin I encounters the stop if the finger plate is overrotated, arresting its motion and preventing damage to the coil spring.

In order to prevent distortion and damage to the spring which might be caused by wrenching the finger plate during or after return to a normal position, the screws II are arranged to project through holes in the upper surface of the stop member l0, which is made of fiat material bent at its fixing end through These holes permit free bending of the spring about the fixing point thereof, but prevent sideways or transverse movement of the top portion of the stop as a whole, due to the aforesaid wrenching action.

By means of the construction described above, it is possible to provide an impulse sender in which the governor mechanism 15 and associated gearing are enclosed in the base plate in such a manner that no holes are required for adjustment purposes, this being advantageous in exeluding dust from the said mechanism.

I claim:

1. In an impulse sender having a central shaft rotated by a finger hole dial, a pin mounted on the shaft and movable therewith, a flat stop member fixed at one end having a catch, a stop screw projecting from the rear of said sender, said stop member tensioned so that the free end lies against said stop screw and moves therewith when the screw is turned to bring the catch into and out of the path of the pin.

2. In an impulse sender comprising a casing having a gear within the casing and a shaft carrying said gear and rotated by the finger plate of the sender, a pin carried by the gear, a spring member mounted on the inside of the casing and having a catch adapted to engage said pin to prevent rotation thereof, a screw having its head on the outside of the casing and its threaded end projecting into the casing, said spring member tensioned to lie against the threaded end of said screw and moved when the screw is turned to withdraw the catch from engagement with said pin.

3. In an impulse sender having a casing and a shaft rotated by the finger plate of the sender, a stop pin on the shaft Within the casing, a stop member within said casing engaging said pin, a screw having its head accessible to the outside of the casing, said stop member tensioned to normally engage the end of said screw and to disengage the stop member from said pin when the screw is turned.

CHARLES CLARKE PUCKETTE. 

